Electrical stimulation of iliohypogastric nerve to alleviate chronic pelvic pain

ABSTRACT

The disclosure describes a method and system for applying electrical stimulation to an iliohypogastric nerve of a patient. The system includes electrical stimulators that apply electrical stimulation for alleviation of pelvic pain. The system may apply electrical stimulation for pelvic pain in men or women. The electrical stimulators may comprise various types of electrodes such as cuff electrodes, electrode leads, and microstimulators implanted at various locations proximate to a single or both iliohypogastric nerves of a patient. In particular, the electrode may be implanted proximate or adjacent to an anterior cutaneous branch of one or both iliohypogastric nerves, a lateral cutaneous branch of one or both iliohypogastric nerves, or one or both of iliohypogastric nerves above the branch point.

TECHNICAL FIELD

The invention relates to medical devices and, more particularly, todevices for delivering neurostimulation therapy.

BACKGROUND

Pain in the pelvic region, including urogential pain, may be caused by avariety of injuries or disorders in men and women. For example,iliohypogastric neuralgia, ilioinguinal neuralgia, genitofemoralneuralgia, chronic groin pain, chronic testicular pain (CTP), postvasectomy pain, and other pain originating from the testicles, groin, orabdomen are common reasons for referral to a urological specialist.

As an example, iliohypogastric, ilioinguinal, and genitofemoralneuralgia may be attributed to nerve injury, such as stretching of anerve, electrocoagulation, stricture caused by ligation, entrapment ofthe nerve in scar tissue, or irritation because of proximity to a zoneof inflammation, during inguinal herniorrhaphy. In addition toherniorrhaphy, other abdominal procedures that may cause theseneuralgias or CTP include appendectomy, iliac crest bone graftharvesting, urological operations, and gynecological surgery, includingtransverse or paramedian incisions for hysterectomy. The painexperienced by the patient may be unilateral or bilateral, constant orintermittent, spontaneous or exacerbated by physical activities andpressure, and may remain localized in the scrotum or radiate to thegroin, perineum, back, or legs.

Typically, denervation procedures are used to treat various neuralgias.In denervation procedures, the nerve that is diagnosed as the cause,e.g., using the results of the patient history, physical examination,preoperative electromyography, and nerve blocks, is severed orpermanently removed. Such procedures may result in permanent andsubstantial pain relief regardless of the origin of pain. However,severing or removing some nerves may result in loss of sensation.Therapeutic nerve blocks may also be used to treat various neuralgias,but generally only relieve pain temporarily.

In addition, women may experience various types of sources of pelvicpain. Sources of pain may include injury to nerves resulting fromsurgical procedures, non-surgical conditions, vulvodynia which can bevery debilitating but has no obvious source, and interstitial cystitis(painful bladder syndrome). Interstitial cystitis may be a source ofpelvic pain in both women and men. Surgical procedures that may injurenerves in the pelvic region may include urological operations in thepelvic area, gynecological surgery, and hysterectomy. Non-surgicalconditions which cause pain in women include adhesions, endometriosis,and pelvic congestion.

SUMMARY

In general, the invention is directed to techniques for applyingelectrical stimulation to an iliohypogastric nerve of a patient via animplantable electrical stimulation device to alleviate symptoms ofchronic pelvic pain in men or women. Pelvic pain may include urogenitalpain or other forms of pelvic pain. The electrical stimulation may beapplied to one or both iliohypogastric nerves.

A system according to the invention may include one or more electricalstimulators that apply electrical stimulation to the iliohypogastricnerve to alleviate chronic groin pain or other afflictions associatedwith pelvic pain, including pain originating from the testicles, groin,or abdomen, such as post vasectomy pain and iliohypogastric neuralgia.In female patients, an electrical stimulator delivers the stimulation tothe iliohypogastric nerve to alleviate other types of pelvic pain suchas vulvodynia, interstitial cystitis, post-operative pain, adhesions,endometriosis or pelvic congestion.

The electrical stimulators may comprise various types of electrodes suchas cuff electrodes, electrode leads, and/or microstimulators implantedat various locations proximate to one or both of the iliohypogastricnerves of a patient. For example, the electrical stimulators may beimplanted proximate to the anterior cutaneous branch of one or both ofthe iliohypogastric nerves of a patient or the lateral cutaneous branchof one or both of the iliohypogastric nerves. The electrical stimulatorsmay alternatively or additionally be implanted proximate to one or bothof the iliohypogastric nerves above the branch point i.e., the point atwhich the iliohypogastric nerve branches to form the anterior cutaneousand lateral cutaneous branches. In this manner, stimulation may beapplied uni-laterally (to one nerve or branch) or bi-laterally (to bothcords or branches).

In some embodiments, electrical stimulation electrodes may be coupled toan implantable stimulation device implanted within a subcutaneous pocketin the abdomen of the patient or, alternatively, the scrotum or buttockof the patient. The electrical stimulation electrodes may be coupled tothe implantable medical device via standard implantable electrode leads.Alternatively, leadless microstimulators may be positioned adjacent thetarget nerves. In this case, the leadless microstimulators may becapable of wireless communication with other implantable medicaldevices, an external programmer, or both.

For male patients, stimulation electrodes or leadless microstimulatorsmay be implanted using well known surgical procedures such as those usedin repairing an inguinal hernia, exposing the spermatic cord, oriliohypogastric denervation. Systems including such electrodes ormicrostimulators and employing the techniques described in thisdisclosure may substantially reduce or eliminate chronic pelvic pain,including urogenital pain such as chronic groin pain or iliohypogastricneuralgia, without loss of sensation in the thigh, penis, and/orscrotum.

Systems according to the invention may include an external programmerthat programs the electrical stimulators to apply electrical stimulationto an iliohypogastric nerve. During stimulation, a clinician or patientmay operate the external programmer to adjust stimulation parameters,such as amplitude, pulse width, pulse rate, and electrode polarities. Insome cases, a patient may use the programmer to deliver stimulation ondemand, e.g., when the patient experiences discomfort. Additionally oralternatively, the implantable stimulation device may store stimulationprograms and schedules. In this manner, the electrical stimulation canbe delivered according to preprogrammed stimulation parameters andschedules, if desired.

In one embodiment, the invention provides a method comprising applyingelectrical stimulation to an iliohypogastric nerve of a patient via animplanted electrical stimulation device.

In another embodiment, the invention provides a system comprising animplantable electrical stimulation device that generates electricalstimulation selected to alleviate pelvic pain, and an electrode coupledto the electrical stimulation device at a position adjacent to aniliohypogastric nerve of a patient.

In a further embodiment, the invention provides a method comprisingapplying electrical stimulation to at least a portion of aniliohypogastric nerve of a patient via an implanted electricalstimulation device.

In another embodiment, the invention provides a system comprising animplantable electrical stimulation device that generates electricalstimulation selected to alleviate pelvic pain, and an electrode coupledto the electrical stimulation device at a position adjacent to aniliohypogastric nerve of a patient.

In various embodiments, the invention may provide one or moreadvantages. For example, applying electrical stimulation to aniliohypogastric nerve of a patient may substantially reduce or eliminatepelvic pain such as that caused by chronic groin pain, post vasectomypain, iliohypogastric neuralgia, and other conditions that cause longterm pain in the testicles, groin, or abdomen, as well as other forms ofpelvic pain experienced by female patients.

Iliohypogastric denervation procedures that sever or remove theiliohypogastric nerve often result in unwanted side effects includingloss of sensation in thigh, penis, and/or scrotum. Therapeutic nerveblocks typically only relieve pain temporarily. In contrast, delivery ofelectrical stimulation to one or both iliohypogastric nerves may providepermanent or long-lived effective therapy for many patients with feweror no unwanted side effects.

In addition, for male patients, electrical stimulators may be implantedproximate to the iliohypogastric nerve using well known surgicalprocedures for repairing an inguinal hernia, exposing the spermaticcord, or iliohypogastric denervation, thereby providing ease ofdeployment by experienced surgeons or other caregivers.

The details of one or more embodiments of the invention are set forth inthe accompanying drawings and the description below. Other features,objects, and advantages of the invention will be apparent from thedescription and drawings, and from the claims.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic diagram illustrating an example system thatincludes an implantable stimulation device for applying electricalstimulation to an iliohypogastric nerve of a patient for alleviation ofpelvic pain from a front view of a male patient.

FIG. 2 is a schematic diagram further illustrating the example system ofFIG. 1 from a side view of a male patient.

FIGS. 3A, 3B and 3C are schematic diagrams illustrating an example cuffelectrode useful in the system of FIGS. 1 and 2.

FIG. 4 is a block diagram illustrating an example implantablestimulation device for applying electrical stimulation to theiliohypogastric nerve of a patient.

FIG. 5 is a block diagram illustrating an example clinician programmerthat allows a clinician to program electrical stimulation therapy for apatient.

FIG. 6 is a schematic diagram illustrating another example systemincluding two different types of electrical stimulators for applyingelectrical stimulation to an iliohypogastric nerve of a patient from afront view of a male patient.

FIG. 7 is a schematic diagram further illustrating the example system ofFIG. 6 from a side view of a male patient.

FIGS. 8A and 8B are schematic diagrams illustrating an example electrodelead of FIGS. 6 and 7.

FIG. 9 is a schematic diagram further illustrating the example system ofFIG. 6.

FIGS. 10A, 10B and 10C are schematic diagrams illustrating an exampleleadless microstimulator suitable for use in the system of FIGS. 6 and7.

FIG. 11 is a side cross-sectional view of a leadless electricalmicrostimulator implanted within tissue proximate to the iliohypogastricnerve of a patient.

FIG. 12 is a schematic diagram illustrating implantation of a leadlessmicrostimulator within tissue proximate to the iliohypogastric nerve.

FIG. 13 is a functional block diagram illustrating various components ofthe leadless microstimulator of FIG. 11.

FIG. 14 is a schematic diagram illustrating another configuration forthe example system of FIG. 7.

FIG. 15 is a flow chart illustrating a technique for applying electricalstimulation to an iliohypogastric nerve of a patient for alleviation ofpelvic pain.

DETAILED DESCRIPTION

FIG. 1 is a schematic diagram illustrating an example system 2 thatincludes an implantable medical device (IMD) 28 in the form of anelectrical stimulator that applies electrical stimulation to one or bothiliohypogastric nerves, the anterior cutaneous branch of one or bothiliohypogastric nerves, or the lateral cutaneous branch of one or bothiliohypogastric nerves of a patient 10. In FIG. 1, system 2 isillustrated from a front view perspective of patient 10. Although theinvention may be generally applicable to treat pelvic pain in both menand women, application of the invention to men will be describedthroughout this disclosure for purposes of illustration. Throughout thefigures accompanying this disclosure, various anatomical features ofpatient 10 and structural features of system 2 are illustratedconceptually for ease of illustration. Accordingly, the figures may notnecessarily present appropriate scales and proportions of suchanatomical features. Rather, the drawings are provided as a conceptualrendering of such features to aid in the understanding of pertinentembodiments of the invention.

In the example of FIG. 1, IMD 28 applies electrical stimulation topatient 10 for alleviation of chronic groin pain, post vasectomy pain,iliohypogastric neuralgia, or other conditions that cause long term(chronic) pain in the testicles (in a male patient), groin, or abdomen.As an example, chronic groin pain may be attributed to nerve injury,such as stretching of a nerve, electrocoagulation, stricture caused byligation, entrapment of the nerve in scar tissue, or irritationproximate to a zone of inflammation during inguinal herniorrhaphy orother previous surgical interventions. In addition to herniorrhaphy,other abdominal procedures that may cause chronic groin pain oriliohypogastric neuralgia include appendectomy, iliac crest bone graftharvesting, and urological operations. In particular, damage to theiliohypogastric nerve may cause a patient to experience pain in thethigh, penis, and/or associated scrotal area. IMD 28 may also deliverstimulation to patient 10 for alleviation of chronic pelvic pain that isidiopathic in origin. Stimulation parameters such as amplitude, pulsewidth and pulse rate may be selected as appropriate to alleviate painfor the particular patient 10.

In additional embodiments, IMD 28 applies electrical stimulation to afemale patient (not shown) for alleviation of pelvic pain such as,urogenital pain and idiopathic pain. Examples of pain include painresulting from surgical procedures, non-surgical procedures, vulvodynia,and interstitial cystitis (painful bladder syndrome). Nerve injury maybe caused by various surgical procedures including urological operationsin the pelvic area, gynecological surgery, and hysterectomy.Non-surgical conditions which cause pain in women include adhesions,endometriosis, and pelvic congestion. Applying electrical stimulation tothe anterior or lateral cutaneous branch of the iliohypogastric nerve orto the iliohypogastric nerve above the branch point in accordance withselected stimulation parameters may alleviate pain experienced by femalepatients.

FIG. 1 illustrates anterior cutaneous branches 34, 35 and lateralcutaneous branches 36, 37 of iliohypogastric nerves 32, 33,respectively. In addition, FIG. 1 illustrates other nerves in theinguinal region of patient 10, e.g., ilioinguinal nerves 30, 31 andgenital branches 22, 23 and femoral branches 24, 25 of genitofemoralnerves 20, 21, respectively. Spermatic cords 14, 15 include a portion ofgenital branches 22, 23, of genitofemoral nerves 20, 21, respectively.Generally, IMD 28 delivers electrical stimulation to anterior cutaneousbranches 34, 35 of iliohypogastric nerves 32, 33 via electrodes whichmay be coupled to IMD 28 by one or more leads. The electricalstimulation has parameters selected to block pain signals from theabdomen and, in some cases, testicles 12 and 13, and/or the associatedscrotal area 11 from reaching the central nervous system (CNS). As shownin the illustrated example of FIG. 1, the electrodes may be configuredto at least partially engage a portion of the anterior cutaneousbranches 34, 35. However, the invention is not so limited. Rather, theinvention also includes embodiments in which electrodes may be implantedproximate to lateral cutaneous branches 36, 37 or iliohypogastric nerves32, 33, i.e., above the branch point of anterior cutaneous branches 34,35, respectively. In the illustrated example of FIG. 1, a dotted circleindicates an example stimulation site along iliohypogastric nerves 32,33.

Further, the invention includes embodiments in which an electrode isimplanted proximate to at least one of iliohypogastric nerve 32,iliohypogastric nerve 33, anterior cutaneous branch 34, anteriorcutaneous branch 35, lateral cutaneous branch 36, and lateral cutaneousbranch 37. For example, electrodes may be implanted proximate toiliohypogastric nerve 32 and proximate to anterior cutaneous branch 34.In another example, electrodes may be implanted proximate toiliohypogastric nerve 32 and proximate to lateral cutaneous branch 36.In yet another example, electrodes may be implanted proximate toanterior cutaneous branch 34 and proximate to lateral cutaneous branch36. The invention further includes embodiments in which electrodes areimplanted bi-laterally in any combination. Such embodiments are includedwithout exhaustively listing all possible combinations. Accordingly, thepositions of electrodes 16 and 17 in FIG. 1 are merely exemplary.

The pain experienced by the patient may be unilateral or bilateral,constant or intermittent, spontaneous or exacerbated by physicalactivities and pressure, and may remain localized or radiate outward. Ina male patient, for example, pain may remain localized in the penis, orradiate to the scrotum, thighs, perineum, or back. Delivering electricalstimulation may cause paresthesia in penis 8, thighs 6, 7, testicles 12and 13 and associated scrotal region 11 based on the position of theelectrodes. The number and position of the leads may be dependent on thepain perceived by the patient and the type of electrical stimulationdelivered to treat the pain. Additionally, the leads coupled to IMD 28may include various types of electrodes depending on the type ofstimulation delivered and the location of the lead.

In the illustrated example, IMD 28 is coupled to leads 18 and 19. Leads18 and 19 each include a cuff electrode, i.e., cuff electrodes 16 and17, that delivers electrical stimulation therapy to iliohypogastricnerves 32 and 33, respectively. A cuff electrode includes a cuff-likefixation structure and one or more electrodes carried by the fixationstructure. In the example of FIG. 1, leads 18 and 19 are implanted atdifferent locations along iliohypogastric nerves 32 and 33,respectively. As a result, patient 10 may experience paresthesia indifferent areas on each side of his body in response to electricalstimulation delivered by electrodes 16 and 17.

Although cuff electrodes are shown in FIG. 1, the leads coupled to IMD28 may include various types of electrodes depending on the type ofstimulation delivered and the location of the lead. For example, IMD 28may be coupled to any number and any type of electrodes, such asconventional ring electrode leads, paddle electrode leads, and otherelectrodes suitable for delivering electrical stimulation toiliohypogastric nerves 32, 33. In addition, in some cases, leadlessstimulators may be used. A cuff electrode may provide more directelectrical contact, i.e., better electrical coupling, with aniliohypogastric nerve than a standard electrode lead. However, in somecases, applying electrical stimulation directly to a nerve may result inthe patient experiencing an unpleasant sensation, such as a burningsensation. Consequently, a standard electrode implanted proximate to theiliohypogastric nerve lead may be advantageous because the patient mayexperience a more pleasant paresthesia as a result of stimulation. Inaddition, a standard electrode lead may also be advantageous in terms ofsurgical ease.

As an example, FIG. 6 illustrates another system in which an IMD iscoupled to an electrode lead having electrodes on the distal end of thelead to stimulate an iliohypogastric nerve of a patient. FIG. 6 alsoillustrates a leadless microstimulator implanted within the tissueadjacent to the iliohypogastric nerve. In this case, an IMD or externalprogrammer may wirelessly control the leadless microstimulator todeliver electrical stimulation to the adjacent tissue. In addition,although not illustrated, an IMD may also be coupled to an electrodesuitable for applying electrical stimulation to genital branches 22, 23and/or femoral branches 24, 25, of genitofemoral nerves 20, 21 orilioinguinal nerves 30, 31.

With further reference to FIG. 1, IMD 28 may be coupled to deliverelectrical stimulation energy to iliohypogastric nerves 32, 33 via cuffelectrodes 16, 17, respectively. Cuff electrodes 16 and 17 each maycomprise a rigid or flexible cuff electrode, a self-sizing spiral cuffelectrode, a half cuff electrode, a helical electrode, a chamberedelectrode, or other types of cuff electrodes that are shaped, sized andotherwise configured to at least partially wrap around aniliohypogastric nerve. The cuff electrode may be sized and shaped to atleast partially enclose the iliohypogastric nerve and promote electricalcoupling pressure between the electrode and the iliohypogastric nerve.The cuff electrodes 16, 17 may each include a single electrode ormultiple electrodes. For example, a cuff electrode 16, 17 may include abipolar or multipolar arrangement of electrodes or a unipolar electrodethat is referenced to the electrical potential of an active canelectrode carried by IMD 28.

IMD 28 includes electrical stimulation pulse generator circuitry anddelivers electrical stimulation in the form of electrical pulses inaccordance with stored stimulation parameters, e.g., electrodecombination, electrode polarity, pulse amplitudes, pulse widths, pulserates, and/or duty cycle. By way of example, the electrical stimulationmay include stimulation pulses having pulse widths between approximately10 and 5000 microseconds, more preferably between approximately 100 and1000 microseconds, and still more preferably between 180 and 450microseconds. The stimulation pulses may define voltage amplitudesbetween approximately 0.1 and 50 volts, more preferably betweenapproximately 0.5 and 20 volts, and still more preferably betweenapproximately 1 and 10 volts. The pulses may have frequencies betweenapproximately 0.5 and 500 hertz, more preferably between approximately10 and 250 hertz, and still more preferably between approximately 50 and150 hertz. The pulses may be alternating current (ac) pulses or directcurrent (dc) pulses, and may be mono-phasic, bi-phasic, or multi-phasicin various embodiments.

IMD 28 may drive electrodes 16 and 17 with the same or differentstimulation pulses or waveforms. In some embodiments, IMD 28 may causeelectrodes 16 and 17 to deliver electrical stimulation simultaneously,or in an interleaved or alternating fashion. For example, electrodes 16and 17 may deliver electrical stimulation with different pulse rates,duty cycles or scheduled times for delivery, which may result inalternating delivery of stimulation. Interleaved or alternating deliveryof stimulation may, for example, reduce the likelihood that neuralaccommodation or tolerance will impair the efficacy of the stimulation.Interleaved or alternating delivery of stimulation may also result inmore complete pain relief than would be possible through delivery ofstimulation via only one electrode or electrode array. Interleavedstimulation may be delivered via conventional ring electrodes, paddlelead electrodes, cuff electrodes, microstimulators, or the like.

Leads 18 and 19 may be implanted proximate to iliohypogastric nerves 32,33, respectively. In the illustrated example, lead 18 is implantedproximate to a region of iliohypogastric nerve 32 and lead 19 isimplanted proximate to a different region of iliohypogastric nerve 32.Specifically, lead 18 is implanted proximate to a subcutaneous region ofiliohypogastric nerve 32 located between the transverses and internaloblique muscles and lead 19 is implanted proximate to a cutaneous regionof iliohypogastric nerve 33 after piercing the internal oblique byperforating the aponeurosis of the external oblique approximately 2.5 cmabove the subcutaneous inguinal ring. However, the invention is notlimited as such. Rather, lead 18 may be implanted at various locationsalong iliohypogastric nerves 32, 33, including anterior cutaneousbranches 34, 35 and lateral cutaneous branches 36, 37 of iliohypogastricnerves 32, 33, respectively, or sympathetic nerves (not shown). Thepositions of leads 18 and 19 in FIG. 1 are shown for purposes ofillustration to show different possible implantation locations andassociated target stimulation sites. Specifically, leads 18 and 19illustrate two locations which may be particularly advantageous forapplying electrical stimulation, which will be described in detailbelow. However, IMD 28 may be coupled to a single lead or a plurality ofleads based on the perceived pain of the patient and his response toelectrical stimulation therapy.

The following is a general anatomical description of theiliohypogastric, ilioinguinal, and genitofemoral nerves that may be usedfor reference. However, the iliohypogastric, ilioinguinal, andgenitofemoral nerves have been demonstrated to have a variable origin,course, and distribution in the inguinal region among differentpatients. In other words, anatomical variability may be observed frompatient to patient. Accordingly, the drawings are provided as aconceptual representation to aid in the understanding of pertinentembodiments of the invention, but not necessarily as an accurateanatomical guide.

In FIG. 1, iliohypogastric nerves 32, 33, ilioinguinal nerves 30, 31,and genital branches 22, 23 and femoral branches 24, 25 of genitofemoralnerves 20, 21 are illustrated. FIG. 1 also illustrates inguinal canals26 and 27. Although not explicitly shown in FIG. 1, the ilioinguinalnerves 30, 31 originate from the L1 and T12 nerves and also, in somecases, the L2 nerve. Generally, the ilioinguinal nerves runsubperitoneally below the respective iliohypogastric nerves. Theilioinguinal nerves emerge from the lateral border of the psoas muscle(not shown) and pierce the transverses abdominis muscle (not shown)approximately one centimeter (cm) above the anterior superior iliacspine (not shown) and then cross the internal abdominal oblique muscle(not shown). The ilioinguinal nerves continue beneath the aponeurosis ofthe external oblique abdominal muscle (not shown) in the direction ofthe symphysis and pubic region.

The ilioinguinal nerves then lie medially, or less frequently, below orlateral to the spermatic cord in men or to the round ligament of theuterus in women and accompany the spermatic cord for approximately twoto four centimeters through the respective inguinal canal ring 26, 27through the internal inguinal ring. Often, the ilioinguinal nerve has areciprocal relationship with regard to the diameter of theiliohypogastric nerve. In some cases, branches of the ilioinguinalnerves fan out and innervate the respective spermatic cord. Branches ofthe ilioinguinal nerves may pierce the oblique muscle aponeurosis tosupply the sensory distribution to the skin of the superomedial thigh aswell as to the root of the penis and the scrotum in men and to the skinof the mons pubis and labia majora in women.

For reference, the iliohypogastric nerves 32, 33 originate from theanterior branch of the L1 nerve and, frequently, the T12 nerve. Theiliohypogastric nerves emerge along the lateral margin of the psoasmuscle (not shown) to pass anterior to the quadratus lumborurn (notshown). The iliohypogastric nerves perforate the transverses abdominismuscle (not shown) above the iliac crest (not shown) as in theilioinguinal nerves. Approximately three centimeters to the anteriorsuperior iliac spine, the iliohypogastric nerves may be found betweenlayers of the transversus and internal oblique muscles (not shown). Theiliohypogastric nerves divide between the transverus abdominis muscleand the internal oblique muscle into lateral and cutaneous branches.

The lateral cutaneous branch pierces the internal and external obliquemuscles. The lateral cutaneous branch is then distributed to the skin ofthe gluteal region. The anterior cutaneous branch continues between thetransverses and internal oblique muscles. In FIG. 1, electrode 16 isillustrated as being implanted proximate to anterior cutaneous branch 34within this region. The anterior cutaneous branch pierces the internaloblique muscle and becomes cutaneous by perforating the aponeurosis ofthe external oblique approximately two to three centimeters above theinternal ring of the inguinal canal and is distributed to the skin ofthe hypogastric region, i.e., the skin of the superomedial thigh, rootof the penis, testicles, and associated scrotal region. Electrode 17 isillustrated as being implanted within this region of anterior cutaneousbranch 35 in FIG. 1.

Genitofemoral nerves 20, 21 originate from the L1 and L2 nerves in thelumbar region (lower back) at L1/L2. As the genitofemoral nerves passthrough the lumbar region, the genitofemoral nerves cross behind theureter (not shown). Slightly posterior to and at a variable distanceabove the inguinal ligament (not shown), the genitofemoral nerves divideinto genital branches and femoral branches. The genital branches crossthe transverses abdominus (not shown) and internal oblique muscles (notshown) and enter the respective inguinal canals through the internalinguinal ring.

Within the inguinal canal, genital branches run along the respectivespermatic cord. The spermatic cord includes various layers (not shown).These layers are the external spermatic fascia, cremasteric muscle andfascia, ilioinguinal nerve (in some cases), internal spermatic fascia,ductus deferens, lymph vessels, pampiniform plexus of veins which becomethe testicular vein, and testicular artery. More specifically, as thestructures within the spermatic cord pass through the transversalisfascia (not shown), they join with one of the layers of the spermaticcord, the internal spermatic fascia.

In a male patient, as the spermatic cord continues through the inguinalcanal, it joins with the cremasteric layer of muscle and fascia from theinternal oblique muscle. These muscle fibers perform an importantreflex, i.e., the cremasteric reflex. When the cremasteric musclecontracts, the testicle is pulled closer to the body. This reflex keepsthe testicles at the correct temperature, for example, by relaxing whenthe testicles are too warm and contracting when the testicles are toocold. If the cremasteric reflex is absent or functions incorrectly,e.g., due to denervation or resection, the male may experience fertilityrelated issues.

Finally, when the spermatic cord passes through the superficial ring, itjoins an external spermatic fascia layer derived from the aponeurosis ofthe external oblique. After the spermatic cord traverses the inguinalcanal, it leads into the scrotum and to the testes where the genitalbraches of the genitofemoral nerves innervate the testes.

In the illustrated example, cuff electrode 16 is wrapped around asubcutaneous portion of anterior cutaneous branch 34 of iliohypogastricnerve 32 and is connected to IMD 28 via lead 18 and, optionally, a leadextension (not shown). The electrical stimulation applied by cuffelectrode 16 stimulates anterior cutaneous branch 34 of iliohypogastricnerve 30.

Electrode 17, in the illustrated example, also comprises a cuffelectrode. More specifically, cuff electrode 17 is wrapped around acutaneous portion of anterior cutaneous branch 35 of iliohypogastricnerve 33. Because cuff electrode 16 is located higher (upstream in thecentral nervous system) from cuff electrode 17, patient 10 mayexperience paresthesia over a larger area, which may be advantageous insome instances. Iliohypogastric nerves 32, 33, however, may not includean external fascia or other tissue to serve as a protective layer.Consequently, wrapping cuff electrodes 16 and 17 around iliohypogastricnerves 32 and 33 may inherently have a risk of pinching or otherwisedamaging the nerve, possibly reducing the long-term efficacy of theelectrical stimulation. As a result, care may be necessary when wrappinga cuff electrode around an iliohypogastric nerve.

The positions of electrodes 16, 17 in FIG. 1 are for purposes ofillustration of different possible positions. In practice, one or bothelectrodes 16, 17 may be positioned within a subcutaneous region oranterior region of the nerve. Alternatively, one or both electrodes 16,17 may be positioned within a cutaneous or distal end of the nerve. Asdiscussed previously, electrodes may be positioned based on the painperceived by the patient and the type of electrical stimulationdelivered to treat the pain. In general, electrodes may be implantedproximate to a portion of the iliohypogastric nerve to apply electricalstimulation for treatment of chronic groin pain or iliohypogastricneuralgia.

In general, it may be difficult to wrap a cuff electrode around theiliohypogastric nerve within a subcutaneous region of the anteriorcutaneous branch. Consequently, stimulation of the anterior cutaneousbranch may preferably be applied to a cutaneous portion of the anteriorcutaneous branch located at a more distal end of the iliohypogastricnerve. Additionally or alternatively, stimulation may be applied to theiliohypogastric nerve above (superior) the branch point of the nerve,i.e., before the nerve branches into the anterior and lateral cutaneousbranches. Stimulation may also be applied to a lateral cutaneous branchof the iliohypogastric nerve depending on the pain experienced by thepatient

Leads 18 and 19 are typically either surgically implanted or insertedpercutaneously. Leads 18 and 19 may be surgically implanted using wellknown surgical techniques. For example, the surgical procedure forneurectomy of the iliohypogastric nerve is well defined, i.e., anabdominal incision as used for neurectomy of the iliohypogastric nerveor hernia repair to expose the iliohypogastric and/or ilioinguinal nerveat the point of muscle emergence. A surgical procedure foriliohypogastric and ilioinguinal neurectomy is described in detail inJudith A. Murovic et. al, “Surgical Management of 33 Ilioinguinal andIliohypogastric Neuralgias at the Louisiana State University HealthSciences Center,” Neurosurgery, Volume 56, Number 5, pages 1013-1020,May 2005. Prior to surgically implanting electrodes, local nerve blocksmay be performed using a nerve blocking agent to determine the precisenerve involved in the pain experienced by the patient. If aniliohypogastric nerve block ameliorates the patient's pain, a surgeonmay conclude that electrical nerve stimulation is likely to beefficacious, and may proceed to surgically implant electrodes inaccordance with the invention. Alternatively, a clinician may stimulatethe patient using an insulated needle to determine the nerve involvedand the placement of an electrode. The diagnosis may also be made usingthe results of the patient history, physical examination, andpreoperative electromyography.

IMD 28 may be implanted at a site in patient 10 near iliohypogastricnerves 32 and 33. The implantation site may be a subcutaneous locationin the side of the lower abdomen. Alternatively, IMD 28 may be implantedwithin the scrotum or buttock of the patient. IMD 28 may be miniaturizedto allow IMD 28 to be implanted within the scrotum. In any case, thesurgeon may then tunnel a lead through tissue and subsequently connectthe lead to IMD 28, with or without a lead extension. IMD 28 may beconstructed with a biocompatible housing, such as titanium or stainlesssteel, much like a conventional neurostimulator such as those used forspinal cord stimulation or pelvic stimulation, e.g., for relief ofchronic pain, sexual dysfunction, or urinary or fecal incontinence.

External programmer 29 may control delivery of electrical stimulation byIMD 28. For example, in some embodiments, external programmer 28 maycomprise a clinician programmer or a patient programmer. A clinicianprogrammer may be a handheld computing device including a display, suchas an LCD or LED display, to display electrical stimulation parameters.A clinician programmer may also include a keypad, which may be used by auser to interact with the clinician programmer. In some embodiments, thedisplay may be a touch screen display, and a user may interact with theclinician programmer via the display. A user may also interact with theclinician programmer using peripheral pointing devices, such as a stylusor mouse. The keypad may take the form of an alphanumeric keypad or areduced set of keys associated with particular functions.

A clinician (not shown) may use the clinician programmer to programelectrical stimulation to be delivered to patient 10. In particular, theclinician may use the clinician programmer to select values for therapyparameters, such as pulse amplitude, pulse width, pulse rate, electrodepolarity and duty cycle, for one of or both electrodes 16 and 17. IMD 28may deliver the electrical stimulation according to programs, eachprogram including values for a plurality of such therapy parameters. Inthis manner, IMD 28 controls delivery of electrical stimulationaccording to preprogrammed stimulation programs and schedules.

When implemented as a patient programmer, external programmer 29 may bea handheld computing device. The patient programmer 26 may also includea display and a keypad to allow patient 10 to interact with the patientprogrammer. In some embodiments, the display may be a touch screendisplay, and patient 10 may interact with the patient programmer via thedisplay. Patient 10 may also interact with the patient programmer usingperipheral pointing devices, such as a stylus or mouse.

Patient 10 may use the patient programmer to control the delivery ofelectrical stimulation. In particular, in response to a command frompatient 10, external programmer 29 may activate IMD 28 to deliverelectrical stimulation or, alternatively, deactivate IMD 28 when noelectrical stimulation is desired. Patient 10 may also use the patientprogrammer to select the programs that will be used by IMD 28 to deliverelectrical stimulation. Further, patient 10 may use the patientprogrammer to make adjustments to programs, such as adjustments toamplitude, pulse width and/or pulse rate. Additionally, the clinician orpatient 10 may use a clinician or patient programmer to create or adjustschedules for delivery of electrical stimulation.

IMD 28 and external programmer 29, implemented as a clinician programmeror a patient programmer, communicate via wireless communication. In someembodiments, external programmer 29 communicates via wirelesscommunication with IMD 28 using radio frequency (RF) telemetrytechniques known in the art. The clinician programmer and patientprogrammer may communicate with one another by wireless communication,e.g., to change or update programs. Alternatively, the programmers maycommunicate via a wired connection, such as via a serial communicationcable, or via exchange of removable media, such as magnetic or opticaldisks, or memory cards.

As previously described, leads 18 and 19 may be implanted surgically orpercutaneously. When inserted percutaneously, leads 18 and 19 may beused in conjunction with an external trial stimulator (not shown) inorder to determine if permanent implantation of the electrodes and leadsis an effective treatment for the patient's pain. For example, prior toimplantation of IMD 28, patient 10 may engage in a trial period, inwhich patient 10 receives an external trial stimulator on a temporarybasis. The external trial stimulator is coupled to temporary leads orimplanted leads via a percutaneous lead extension.

The trial neurostimulation permits a clinician to observeneurostimulation efficacy and determine whether implantation of achronic neurostimulation device is advisable. Specifically, the trialneurostimulation period may assist the clinician in selecting values fora number of programmable parameters in order to define theneurostimulation therapy delivered to patient 10. For example, theclinician may select an amplitude, which may be current- orvoltage-controlled, and pulse width for a stimulation waveform to bedelivered to patient 10, as well as a rate, i.e., frequency) deliveredto the patient. In addition, the clinician also selects particularelectrodes on a lead to be used to deliver the pulses, and thepolarities of the selected electrodes.

By stimulating iliohypogastric nerves 32 and 33, a system in accordancewith an embodiment of the invention may substantially reduce oreliminate pelvic pain such as chronic groin pain, post vasectomy pain,iliohypogastric neuralgia, and other conditions that cause long termpain in the testicles, groin, or abdomen. Iliohypogastric denervationprocedures may result in permanent and substantial pain relief but mayalso cause unwanted side effects, such as loss of sensation in the skinof the superomedial thigh, penis, testicle and/or scrotum. Therapeuticnerve blocks may also be used to treat iliohypogastric neuralgia, butgenerally only relieve pain temporarily. Because electrical stimulationdoes not require severing the iliohypogastric nerves cord and, moreparticularly, aims to avoid damaging nerves, the invention may providesimilar or improved pain relief without the unwanted side effects.

FIG. 2 is a schematic diagram further illustrating system 2. Inparticular, system 2 is illustrated from the left side of patient 10.For purposes of illustration, only iliohypogastric nerve 33, anteriorcutaneous branch 35 and lateral cutaneous branch 37 of iliohypogastricnerve 33, genitofemoral nerve 21, genital nerve branch 23 and femoralnerve branch 25 of genitofemoral nerve 21, spermatic cord 15, externalfascia layer 39, inguinal canal 27, testicle 13 and scrotum 11 areshown. In FIG. 2, cuff electrode 16 is illustrated as being wrappedaround anterior cutaneous branch 35 of iliohypogastric nerve 33 belowthe branch point to illustrate the different locations at whichelectrodes may be implanted and to illustrate an embodiment in whichmultiple electrodes are implanted along iliohypogastric nerve 33.Accordingly, an additional cuff electrode 17 is shown as being wrappedaround a portion of iliohypogastric nerve 33 above the branch point ofiliohypogastric nerve 33, while cuff electrode 16 is shown as beingwrapped around a different portion of anterior cutaneous branch 35 ofiliohypogastric nerve 33. Following the convention illustrated in FIG.1, a dotted circle illustrates an example stimulation site at which anelectrode may be implanted on anterior cutaneous branch 35 at a positionproximate to lateral cutaneous branch 37 of iliohypogastric nerve 33 incombination with one or more of electrodes 16 and 17.

In an embodiment in which two or more electrodes are implanted along thesame iliohypogastric nerve 33, the electrodes may form a bipolar pairthat is referenced between two electrodes deployed by leads 18, 19, orbe individually referenced to an electrical potential associated with anelectrode on the housing of IMD 28. Also, in some embodiments, multiplecuffs or leads may be implanted along iliohypogastric nerve 33, and eachmay carry multiple electrodes, e.g., in an axial or planar array,providing still more possible electrode combinations for selection by aphysician.

FIG. 2 illustrates iliohypogastric nerve 33 branching to anteriorcutaneous branch 35 to innervate the skin of the hypogastric region ofpatient 10 and lateral cutaneous branch 37 to innervate the skin of thegluteal region of patient 10. In particular, anterior cutaneous branch35 may innervate portions or regions of penis 8, scrotum 11, and theabdomen of patient 10. Although not shown, branches of iliohypogastricnerve 33 may innervate ilioinguinal nerve 31 in some cases. As shown inFIG. 2, genital nerve branch 23 originates from genitofemoral nerve 21and passes through inguinal canal 27 to innervate testicle 13. Aspreviously described, spermatic cord 15 joins an external fascia layer39 as it passes through the superficial ring of inguinal canal 27.

Cuff electrode 16 is wrapped around an anterior portion of anteriorcutaneous branch 35, i.e., a subcutaneous portion of anterior cutaneousbranch 35 between the transverses and internal oblique muscles.Optionally, another electrode is provided. For example, cuff electrode17 is wrapped around a portion of iliohypogastric nerve 33 above thebranch point of iliohypogastric nerve 33, i.e., a portion ofiliohypogastric nerve 33 before branching into anterior and lateralcutaneous branches 35 and 37, respectively. Because cuff electrode 17 islocated higher (upstream in the central nervous system) from cuffelectrode 16, patient 10 may experience paresthesia over a larger area,which may be advantageous in some instances.

In general, cuff electrodes 16 and 17 may be particularly advantageousbecause cuff electrodes 16 and 17 may remain in place as patient 10moves without requiring any external fixation means such as sutures oranchoring mechanisms. External fixation means may damage tissue or thenerve itself, possibly causing additional pain which may reduce theefficacy of the electrical stimulation therapy. Cuff electrodes 16 and17 include a fixation structure that at least partially wraps aroundiliohypogastric nerve 33. The fixation structure may be fabricated froma flexible biocompatible material that provides a flexible interfacebetween the electrode and iliohypogastric nerve 31.

In some embodiments, the cuff fixation structure may be fabricated froma flexible or rigid biocompatible material. In such cases, the fixationstructure may form a split cylinder or a “U” shape sized to fit aroundiliohypogastric nerve 33. Cuff electrodes 16 and 17 may generallycomprise a rigid cuff electrode, a self-sizing spiral cuff electrode, ahalf cuff electrode, a helical electrode, a chambered electrode, andother types of cuff electrodes that at least partially wrap around oneof iliohypogastric nerves 32 and 33. Upon enclosure of at least aportion of iliohypogastric nerves 32 and 33, a cuff may be held in aclosed position by shape memory properties, sutures, interlocking tabs,surgical adhesive, crimping, or other fixation techniques or structures.

FIGS. 3A, 3B and 3C are schematic diagrams illustrating an exemplaryembodiment of a cuff electrode 16. Cuff electrode 17 may be similarlyconstructed. Cuff electrodes 16 and 17 may be any type of cuff electrodeused to deliver electrical stimulation. In some embodiments, cuffelectrodes 16 and 17 may both comprise the same type of cuff electrodeor may comprise different types of cuff electrodes. In any case, cuffelectrode 16 is merely exemplary and should not be considered limitingof the invention as broadly embodied and described in this disclosure.The purpose of FIGS. 3A-C is to illustrate the implantation of cuffelectrodes to deliver electrical stimulation to the iliohypogastricnerves.

FIG. 3A is a top view of cuff electrode 16. Cuff electrode 16 includeslead 18, fixation structure 40, a plurality of stimulation electrodes48A-C, and a plurality of electrical conductors 46 within lead 18. Inthe example of FIG. 3A, cuff electrode 16 includes three electrodes 48A,48B, 48C. In the illustrated example, electrodes 48A-C is arranged suchthat a major axis of each electrode extends laterally to theiliohypogastric nerve. In this manner, the length of each electrode maybe wrapped about all or a portion of the circumference of theiliohypogastric nerve. The proximal end 44 of lead 18 is connected toIMD 28 and fixation structure 40 is attached to the distal end 42 oflead 18. Cuff electrode 16 may generally include one electrode or aplurality of electrodes.

Each of electrodes 48A-C is coupled to one of a plurality of supplyconductors 46. Electrodes 48A-C may be driven together via a commonconductor or independently via separate conductors. When electrodes48A-C are driven by a common conductor, they may be referenced to one ormore electrodes carried by another lead or one or more electrodescarried by the IMD housing. When electrodes 48A-C are driven by separateconductors, bipolar or multipolar electrode combinations may be formedon a single lead or among two or more leads, as well as between one ormore leads and the IMD housing.

For a given bipolar pair of electrodes on a lead, one supply conductorsources stimulation energy to a first electrode and a second supplyconductor sinks stimulation energy from a second electrode, with thestimulation energy propagating across nerve tissue between the first andsecond electrodes. Hence, one electrode may form a cathode while theother forms an anode. Also, in some embodiments, multiple anodes andcathodes may be used in an electrode combination. A switch device in theIMD determines which electrodes will function as anodes and whichelectrodes will function as anodes.

As previously described, fixation structure 40 may be fabricated from aflexible biocompatible material that provides a flexible interfacebetween the electrode and the iliohypogastric nerve. In someembodiments, fixation structure 40 may be fabricated from a rigidbiocompatible material. The rigid fixation structure may form a splitcylinder or a “U” shape sized to fit around the iliohypogastric nerve.In any case, when implanting electrode 16, the surgeon may elevate theiliohypogastric nerve and wrap fixation structure 40 around theiliohypogastric nerve.

The manner in which the surgeon installs the cuff electrode around theiliohypogastric nerve depends on the type of cuff electrode. Forexample, if fixation structure 40 is fabricated from a shape memoryalloy, fixation structure 40 may recover its shape at a fixedtemperature, e.g., slightly under room temperature. By sufficientlycooling fixation structure 40, the surgeon can easily open the cuff andposition fixation structure 40 under the iliohypogastric nerve. Becausethe nominal body temperature of the patient is above room temperature,fixation structure 40 warms up and recovers its initial shape therebyclosing or wrapping fixation structure 40 around the iliohypogastricnerve. In another example, the fixation structure may be constrained ina flat manner using a surgical tool or hand and, when released, wrapsaround the nerve.

FIG. 3B is a cross sectional view of cuff electrode 16 implantedunderneath iliohypogastric nerve 33. In the illustrated example,fixation structure 40 is flat thereby allowing the surgeon to easilyposition electrode 16 under iliohypogastric nerve 33. When fixationstructure 40 is fabricated from a shape memory alloy material, thesurgeon may cool fixation structure 40 prior to positioning fixationstructure 40 to easily manipulate fixation structure 40 into the openconfiguration shown in FIG. 3B. The surgeon may then position fixationstructure under iliohypogastric nerve 33. Fixation structure 40 willrecover its initial shape, i.e., a substantially closed ring sized tofit around iliohypogastric nerve 31, as fixation structure warms up toits activation temperature.

FIG. 3C is a cross sectional via of cuff electrode 16 implanted andwrapped around iliohypogastric nerve 33. More specifically, FIG. 3Cillustrates the shape of fixation structure 40 when it has returned toits initial shape in response to warming from the patient's body heat.In the illustrated example, a gap 49 may exist between iliohypogastricnerve 33 and fixation structure 40. The gap may be filled with tissue orfluids and may provide a buffer that prevents cuff electrode 16 fromdamaging iliohypogastric nerve 33. Alternatively, fixation structure 40may be sized to wrap around iliohypogastric nerve 33 such that there issubstantially no gap between fixation structure 40 and iliohypogastricnerve 33. In some embodiments, fixation structure may be deployed usingsuperelastic properties of a shape memory allow such as Nitinol. Forexample, the fixation structure may be constrained in a flat shapeeither manually or with a surgical took, and then released so that itwraps around the nerve.

FIG. 4 is a block diagram illustrating an example configuration of IMD28. IMD 28 may apply electrical stimulation to iliohypogastric nerves 32and 33 of patient 10 via electrodes, e.g., electrodes 16 and 17, coupledto IMD 28 via leads 18 and 19, respectively. The configuration, type,and number of electrodes illustrated in FIG. 4 are merely exemplary.Leadless stimulators alternatively may be used instead of or in additionto leads 18, 19 and electrodes 16, 17. A leadless stimulator does notgenerally include any elongated leads, and instead carries electrodes ona housing of the stimulator or on a structure such as a fixation deviceextending from the housing.

In the example of FIG. 4, electrodes 16 and 17 are electrically coupledto a therapy delivery module 52 via leads 18 and 19, respectively.Therapy delivery module 52 may, for example, include an output pulsegenerator coupled to a power source such as a battery and charge storagecapacitor. Therapy delivery module 52 may deliver electrical stimulationpulses to patient 10 via one or both of electrodes 16 and 17 under thecontrol of a processor 54.

Processor 54 controls therapy delivery module 52 to deliver electricalstimulation according to a selected parameter set stored in memory 56.Specifically, processor 54 may control circuit 52 to deliver electricalstimulation pulses with the amplitudes and widths, and at the ratesspecified by the programs of the selected parameter set. Processor 54may also control circuit 52 to deliver each pulse according to adifferent program of the parameter set. Processor 54 may include amicroprocessor, a controller, a digital signal processor (DSP), anapplication specific integrated circuit (ASIC), a field programmablegate array (FPGA), or any other equivalent integrated or discrete logiccircuitry, or the like.

In some embodiments, memory 50 may store parameter sets 58 that areavailable to be selected by patient 10 for delivery of electricalstimulation. Memory 50 may also store schedules 56. Memory 50 mayinclude any combination of volatile, non-volatile, fixed, removable,magnetic, optical, or solid state media, such as a random access memory(RAM), random access memory (ROM), CD-ROM, hard disk, removable magneticdisk, memory cards, non-volatile RAM (NVRAM), electrically programmableROM (EEPROM), flash memory, and the like.

IMD 28 delivers stimulation according to preprogrammed stimulationparameters and, optionally, schedules stored in memory 50. Schedules 56may define times for processor 54 to select particular parameter sets 58and control therapy delivery module to delivery therapy according tothat parameter set. A schedule 56 may cause electrical stimulation to bedelivered via electrodes 16 and 17 at respective times, which mayinclude simultaneous and/or alternate delivery. For example, stimulationmay be activated, deactivated or altered for different times of the day,such as times during which the patient is awake or sleeping, or workingor at rest. A clinician or patient may create, modify, and selectschedules 56 using external programmer 29.

IMD 28 also includes a telemetry circuit 53 that allows processor 54 tocommunicate with external programmer 29, i.e., a clinician programmer orpatient programmer. Processor 54 may receive programs to test on patient10 from external programmer 29 via telemetry circuit 52 duringprogramming by a clinician. Where IMD 28 stores parameter sets 58 inmemory 50, processor 54 may receive parameter sets 58 from externalprogrammer 29 via telemetry circuit 52 during programming by aclinician, and later receive parameter set selections made by patient 10from external programmer 29 via telemetry circuit 52. Where externalprogrammer 29 stores the parameter sets, processor 54 may receiveparameter sets selected by patient 10 from external programmer 29 viatelemetry circuit 52.

FIG. 5 is a block diagram illustrating an example patient or clinicianprogrammer 71 that allows a patient or clinician to program electricalstimulation therapy for a patient. Patient 10 or a clinician mayinteract with a processor 60 via a user interface 62 in order to controldelivery of electrical therapy as described herein. User interface 62may include a display and a keypad, and may also include a touch screenor peripheral pointing devices as described above. Processor 60 may alsoprovide a graphical user interface (GUI) to facilitate interaction withpatient 10, as will be described in greater detail below. Processor 60may include a microprocessor, a controller, a DSP, an ASIC, an FPGA,discrete logic circuitry, or the like.

Programmer 71 also includes a memory 64. In some embodiments, memory 64may store parameter sets 68 that are available to be selected by patient10 or a clinician for delivery of electrical stimulation. Memory 64 mayalso store schedules 66. Hence, parameter sets and schedules may bestored in IMD 28, programmer 71, or both. Programmer 71 also includes atelemetry circuit 70 that allows processor 60 to communicate with IMD28, and, optionally, input/output circuitry 72 (e.g., wired or wirelessI/O media) to allow processor 60 to communicate with another programmer.

Processor 60 may receive parameter set selections made by patient 10 ora clinician via user interface 62, and may either transmit the selectionor the selected parameter set to IMD 28 via telemetry circuitry 70 fordelivery of electrical stimulation according to the selected parameterset. Where programmer 71 stores parameter sets 66 in memory 64,processor 60 may receive parameter sets 66 from another programmer viainput/output circuitry 72 during programming by a clinician. Circuitry72 may include transceivers for wireless communication, appropriateports for wired communication or communication via removable electricalmedia, or appropriate drives for communication via removable magnetic oroptical media.

FIG. 6 is a schematic diagram illustrating another example system 100for applying electrical stimulation to a male patient 10 for pelvic painsuch as chronic groin pain, post vasectomy pain, iliohypogastricneuralgia, and other conditions that cause long term (chronic) pain inthe testicles, groin, or abdomen. System 100 also may be useful foralleviation of pelvic pain for female patients. In the illustratedexample, system 100 includes electrodes 104 deployed on a lead extendingfrom an IMD 108, and a leadless microstimulator 106. Electrodes 104 andleadless microstimulator 106 deliver electrical stimulation toiliohypogastric nerves 33 and 32, respectively, and illustratealternative stimulation arrangements. Hence, stimulation energy may bedelivered to iliohypogastric nerves 32, 33 via any combination of cuffelectrodes, axial electrode arrays (i.e., with ring electrodes), planarelectrode array (e.g., on paddle lead), leadless microstimulators, orother types of electrodes.

IMD 108 controls the delivery of electrical stimulation according topreprogrammed stimulation programs, parameter sets and/or schedules. Inparticular, IMD 108 or external programmer 109 may wirelessly controlmicrostimulator 106 to deliver electrical stimulation to iliohypogastricnerve 30. Alternatively, microstimulator 106 may operate autonomously orin a coordinated manner in conjunction with other microstimulators orIMD 108. In the example of FIG. 6, IMD 108 is also coupled to electrodes104 via lead 102. Again, the invention is not limited to the illustratedconfiguration. In general, IMD 108 may be coupled to any number and typeof electrodes or electrical stimulators. The electrodes may also bepositioned adjacent to one or both iliohypogastric nerves 32, 33 basedon the perceived pain of patient 10. However, FIG. 6 illustrates examplesystem 100 in which microstimulator 106 and electrodes 104 deliverbi-lateral electrical stimulation to iliohypogastric nerves 32 and 33,respectively.

In the illustrated example, microstimulator 106 is implanted adjacent toiliohypogastric nerve 32 and includes a housing and a fixation structureattached to the housing. The housing may be formed into a capsule-likeshape and may be constructed from any of a variety of biocompatiblematerials, such as titanium or stainless steel. As will be described,the housing may carry an implantable pulse generator (IPG) and,optionally, a telemetry interface to exchange (send, receive or both)control signals with other devices such as IMD 108 or externalprogrammer 109. The fixation structure on microstimulator 106 may beconstructed similar to the fixation structure of previously describedcuff electrodes 16 and 17. For example, the fixation structure onmicrostimulator 106 may be constructed of a flexible or a rigidbiocompatible material that at least partially wraps aroundiliohypogastric nerve 32. The fixation structure may carry one or moreelectrodes, i.e., the electrodes may be integrated with the fixationstructure, and the housing may include short leads that extend from thehousing to couple the electrodes to the housing.

Alternatively, leadless microstimulator 106 may be implanted withintissue proximate or adjacent to iliohypogastric nerve 32 using a needle(not shown). In particular, microstimulator 106 may be implanted with aminimally invasive, percutaneous procedure. As an example, the needlemay include a hollow cylinder and a pointed distal end for puncturingskin of patient 10. The needle may include the microstimulator and afluid, e.g., saline solution, or push rod to force the microstimulatorout of the needle. In this case, microstimulator 106 may be miniaturizedin order to be implanted using the needle. In some embodiments, aplurality of microstimulators may be implanted within tissue proximateto the iliohypogastric nerve. The plurality of implantedmicrostimulators may apply electrical stimulation independently or on acoordinated basis.

When implanted within tissue proximate to iliohypogastric nerve 32,microstimulator 106 may comprise a self-contained module. The modulecomprises a housing that may carry one or more electrodes and an IPGwithin the housing. The IPG may comprise a circuit board and a powersource, such as a battery, to provide power to the circuit board andelectrodes. The circuit board may include the telemetry interface andother processing electronics. The electrodes may be pads mounted on asurface of the housing or ring electrodes that extend about the entireperiphery of the housing. In some cases, the housing itself may form anactive “can” electrode in addition to the electrodes mounted on thehousing.

Microstimulator 106 may be implanted with less invasive procedures thanother electrodes that are coupled to an IMD via a lead. For example,because microstimulator 106 may include a self-contained stimulationpulse generator and one or more electrodes, a surgeon does not have totunnel a lead to IMD 108. In some embodiments, microstimulator 106 maywirelessly communicate with external programmer 109. In this case,external programmer 109 may be a small, battery-powered, portable devicethat may accompany patient 10 through the day. External programmer 109may have a simple user interface, such as a button or keypad, and adisplay or lights. Patient 10 may only be able to activate anddeactivate IMD 108. However, in other embodiments, external programmer109 may include additional functionality to operate in a manner similarto a patient programmer.

In the illustrated example, ring electrodes 104 mounted on lead 102 alsomay be used to deliver electrical stimulation to iliohypogastric nerve33. Lead 102 is coupled to IMD 108 and carries electrical conductors totransmit stimulation energy from the IMD to the electrodes 104 on aselective basis. In particular, one or more electrodes may be selectedto form anodes and cathodes for delivery of stimulation energy viaunipolar, bipolar or multipolar electrode combinations. Lead 102 may beimplanted adjacent to iliohypogastric nerve 33 as shown. Lead 102 isshown in FIG. 6 carrying four electrodes, e.g., ring electrodes,although any number of electrodes could be used. Also, as mentionedpreviously, electrodes 104 may be arranged in an axial array, e.g., asring electrodes, or in a two-dimensional planar array, e.g., in a paddlelead. Also, other types of leads providing curved or rounded electrodearrays may be used. At least one conductor is included in lead 102 thatelectrically connects the proximal end of lead 102 to electrodes 104 inits distal end. IMD 108 may control electrical stimulation applied byeach of electrodes 104 separately or control electrical stimulationapplied by a group of electrodes 104.

In some embodiments, lead 102 may be formed to include fixationelements, such as hooks, barbs, helical structures, tissue ingrowthmechanisms, or other anchoring mechanisms, e.g., at a distal end of lead102. Fixation elements may serve to fix electrodes 104, relative toiliohypogastric nerve 33 so that electrodes 104 can provide consistentelectrical simulation. Without anchoring electrodes 104 toiliohypogastric nerve 33 or tissue proximate to iliohypogastric nerve33, the distance between electrodes 104 and iliohypogastric nerve 33 mayvary as patient 10 moves throughout the day, reducing the efficacy ofthe applied electrical stimulation. However, it is possible thatanchoring mechanisms may damage iliohypogastric nerve 33 or surroundingtissue during implantation or as patient 10 moves.

System 100 generally operates in a similar manner to system 2 in FIG. 1to apply electrical stimulation for chronic groin pain, iliohypogastricneuralgia, or other pelvic pain disorders. Accordingly, externalprogrammer 109 may comprise a clinician programmer or a patientprogrammer. As shown, external programmer 109 may communicate viawireless communication with IMD 108. In particular, external programmer109 may control delivery of electrical stimulation by IMD 108 usingtelemetry techniques known in the art. When microstimulator 106comprises a self-contained module, external programmer 109 may directlycommunicate with microstimulator 106 via wireless communication tocontrol delivery of electrical stimulation.

FIG. 7 is a schematic diagram further illustrating example system 100.In particular, system 100 is illustrated from the left side of a malepatient 10 in FIG. 7. For purposes of illustration, only iliohypogastricnerve 33, anterior cutaneous branch 35 and lateral cutaneous branch 37of iliohypogastric nerve 33, genitofemoral nerve 21, genital nervebranch 23 and femoral nerve branch 25 of genitofemoral nerve 21,spermatic cord 15, and testicle 13 are shown. Again, iliohypogastricnerve 33 originates from the L1 and T12 and also, in some cases, the L2nerve. Iliohypogastric nerve 33 innervates penis 8, scrotum 11, and theskin of the hypogastric and gluteal region of patient 10. In some cases,branches of iliohypogastric nerve 33 may also innervate ilioinguinalnerve 31.

In general, electrical stimulation is applied to iliohypogastric nerve33 through electrodes 104 of lead 102 implanted adjacent toiliohypogastric nerve 33. More specifically, electrodes 104 of lead 102are implanted adjacent to anterior cutaneous branch 35 ofiliohypogastric nerve 33. Electrodes 104 apply electrical stimulation toiliohypogastric nerve 33 under control of IMD 108. Lead 102 carrieselectrodes 104 and couples electrodes 104 to IMD 108. In particular, atleast one electrical conductor is included in lead 102 that electricallyconnects electrodes 104 to IMD 108. Electrodes 104 may comprise fourelectrodes, e.g., ring electrodes, although the invention is not solimited. Electrodes 104 may comprise any number and type of electrodes.In some embodiments, as mentioned above, lead 102 also may includefixation elements, such as hooks, barbs, helical structures, tissueingrowth mechanisms, or other anchoring mechanisms that aid in securinglead 102 to iliohypogastric nerve 33 or tissue proximate toiliohypogastric nerve 33. Securing lead 102 to iliohypogastric nerve33or to tissue proximate to iliohypogastric nerve 33 may prevent lead102 from moving relative to iliohypogastric nerve 33.

IMD 108 is programmed to deliver electrical stimulation appropriate forchronic groin pain, post vasectomy pain, iliohypogastric neuralgia, andother conditions that cause long term (chronic) pain in the testicles,groin, or abdomen. IMD 108 may control electrical stimulation applied byeach of electrodes 104 independently. Alternatively, IMD 108 may controlelectrical stimulation applied by a group of electrodes 104, and mayselect different combinations of electrodes 104 in bipolar ormulti-polar arrangements to identify a particular combination that ismost effective in producing desired paresthesia. Again, IMD 108 maycontrol delivery of electrical stimulation according to parameter setsand/or schedules programmed in internal memory.

Although FIG. 7 illustrates lead 102 implanted adjacent to anteriorcutaneous branch 35 of iliohypogastric nerve 33, lead 102 may beimplanted adjacent to lateral cutaneous branch 37 of iliohypogastricnerve 33, or a portion of iliohypogastric nerve 33 above the branchpoint. Again, the region to which electrical stimulation is applied isdetermined by the pain experienced by the patient. Applying electricalstimulation to iliohypogastric nerve 33 at a location further upstreammay cause patient 10 to experience a larger area of paresthesia inresponse to electrical stimulation. In both male and female patients,stimulation may be applied to any portion of iliohypogastric nerve 33.

FIGS. 8A and 8B show exemplary electrical leads with fixation elementsto secure the lead within a patient. As shown in FIG. 8A, lead 110includes lead body 112, tines 116A-D (collectively tines 116) andelectrodes 114A-D (collectively electrodes 114). Lead 110 may be astandard lead that includes all four tines 116 close to electrodes 114.Lead 110 may be implemented with any number of electrodes or tines. Whenimplanting lead 110, having tines 116 close to electrodes 114 may bebeneficial by allowing less movement of electrodes 114 with respect tothe iliohypogastric nerve.

Electrodes 114 are more effective in delivering electrical stimulationwhen the electrodes are located close to the iliohypogastric nerve. Ifelectrodes 114 migrate away from the iliohypogastric nerve, due tomovement of the patient throughout the day, for example, the efficacy ofthe stimulation may decrease. Therefore, tines 116 located close toelectrodes 114 may be beneficial to therapy efficacy.

FIG. 8B illustrates a lead 120 which includes lead body 122, tines 126,and electrodes 124A-D (collectively electrodes 124). Lead 120 may be astandard lead that includes tines 126 located at the distal end of leadbody 122. Lead 120 may be implemented with any number of electrodes ortines. Electrodes 124 may be located close to or a distance away fromtines 126. When electrodes 124 are close to tines 126, implanting lead120 may allow less movement of electrodes 124 with respect to theiliohypogastric nerve. Consequently, the intensity of electricalstimulation delivered to the iliohypogastric nerve may not vary andcause the patient to experience different levels of paresthesia.

When electrodes 124 are located a distance away from tines 126,implanting lead 102 may allow electrodes 124 to reach further away fromthe anchoring site. For example, when lead 102 delivers electricalstimulation to the iliohypogastric nerve, tines may be anchored totissue a distance away from the iliohypogastric nerve while leads may belocated proximate to the iliohypogastric nerve. Securing tines 126 tothe iliohypogastric nerve is undesirable because the nerve may bedamaged in the process. Thus, lead 120 may be beneficial by preventingunwanted nerve damage during the implantation process.

FIG. 9 is a schematic diagram further illustrating example system 100.In particular, system 100 is illustrated from the right side of a malepatient 10. For purposes of illustration, only iliohypogastric nerve 32,anterior cutaneous branch 34 and lateral cutaneous branch 36 ofiliohypogastric nerve 32, genitofemoral nerve 20, genital nerve branch22 and femoral nerve branch 24 of genitofemoral nerve 20, spermatic cord14, testicle 12, and scrotum 11 are shown. As previously described andsimilar to iliohypogastric nerve 33, iliohypogastric nerve 32 originatesfrom the L1 and T12 and also, in some cases, the L2 nerve.Iliohypogastric nerve 32 innervates penis 8, scrotum 11, and the skin ofthe hypogastric and gluteal region of patient 10. In some cases,branches of iliohypogastric nerve 32 may also innervate inguinal nerve30.

Microstimulator 106 applies electrical stimulation to iliohypogastricnerve 32 under control of IMD 108 or external programmer 109. As shown,IMD 108 or external programmer 109 may wirelessly controlmicrostimulator 106 to delivery electrical stimulation. Microelectrode106 includes a housing 107 and a fixation structure 105, such as a cuff,attached to housing 107. Housing 107 may be formed into a capsule-likeshape and may be constructed from any of a variety of biocompatiblematerials, such as titanium. Housing 107 may carry an implantable pulsegenerator (IPG) and a telemetry interface to receive control signalsfrom IMD 108. Fixation structure 105 wraps at least partially aroundiliohypogastric nerve 32 to secure microstimulator 106 in place.Accordingly, fixation structure 105 may operate and be constructedsimilar to the fixation structure of previously described cuffelectrodes 16 and 17. Fixation structure 105 may carry one or moreelectrodes coupled to housing 107 via short leads (not shown). In someembodiments, housing 107 may form an active “can” electrode.

The invention is not limited to the illustrated configuration, i.e.,microstimulator 106 implanted to deliver electrical stimulation toanterior cutaneous branch 34. For example, microstimulator 106 may alsobe implanted, additionally or alternatively, to deliver electricalstimulation to lateral cutaneous branch 36 and iliohypogastric nerve 32above the branch point. In such cases, fixation structure 105 wraps atleast partially around lateral cutaneous branch 36 and iliohypogastricnerve 32, respectively. In addition, in some embodiments, amicrostimulator may be implanted to deliver electrical stimulation atboth locations in a coordinated manner or independently of each other.

FIGS. 10A-10C are enlarged schematic diagrams showing microstimulator106. In particular, FIG. 10A is an enlarged top view of microstimulator106 including housing 107, circuit board 130, power supply 132, fixationstructure 105, and electrodes 108A-C (collectively electrodes 108).Housing 107 may have a rounded, capsule-like shape, and a smooth,atraumatic surface formed of one or more biocompatible materials, suchas titanium, stainless steel, epoxy, or polyvinylchloride. However, theinvention is not so limited. Instead, housing 107 may have a shape thatis compatible with the anatomy at the implant site, i.e., theiliohypogastric nerve. In some embodiments, the leadless microstimulatormay have a capsule shape with a diameter of approximately less than orequal to 2 cm and a length of less than or equal to approximately 5 cm.

Fixation structure 105 may be constructed of a flexible or rigidbiocompatible material that at least partially wraps around theiliohypogastric nerve, e.g., like a cuff. For example, fixationstructure 105 may be fabricated from a shape memory alloy that has thecapacity to recover a memorized shape when deformed at a certaintemperature and then heated at a higher temperature or vice versa. Inthis case, the memorized shape may be a split cylinder or asubstantially closed cylinder with a diameter sized to wrap around theiliohypogastric nerve.

FIG. 10A illustrates fixation structure 105 in a deformed, generallyopen state that enables a surgeon to easily position slipmicrostimulator 106 underneath the iliohypogastric nerve. However, afterpositioning microstimulator 106 beneath the spermatic cord, the bodytemperature of the patient causes fixation structure 105 to recover itsmemorized shape, i.e., a split cylinder. Therefore, fixation structure105 may be beneficial by reducing trauma during surgical implantationprocedures.

Fixation structure 105 also carries one or more electrodes 108.Electrodes 108 may be driven together or independently. For example,electrodes 108 may be selectively driven to form combinations of anodesand cathodes. Electrodes 108 may be integrated with fixation structure105 or, alternatively housing 107 may include short leads (not shown)that extend from housing 107 to couple electrodes 108 to housing 107.

Circuit board 130 may include a processor, memory, pulse generatorcircuitry to generate electrical pulses delivered by 108, and telemetrycircuitry for wireless telemetry with IMD 108, external programmer 109,or both. As an example, the memory may store stimulation parameters,e.g., electrode polarity, pulse width, pulse rate, and amplitude. Memorymay also store schedules which define times for the processor to selectparticular parameters. A schedule may cause electrical stimulation to bedelivered at respective times. In this manner, the processor may controlthe pulse generator circuitry generate electrical stimulation pulses inaccordance with the selected parameters and schedule.

Microstimulator 106 may also operate under control from an externalprogrammer, so that a physician or patient may activate, deactivateand/or modify stimulation delivered to the patient on a selective basis.Power source 132 supplies operating power to circuit board 130 and maytake the form of a small rechargeable or non-rechargeable battery.Different types of batteries or different battery sizes may be used. Topromote longevity, power source 132 may be rechargeable via induction orother means.

FIG. 10B illustrates a cross sectional view of microstimulator 106implanted underneath iliohypogastric nerve 32. In the illustratedexample, fixation structure 105 is flat, thereby allowing the surgeon toeasily position microelectrode 106 underneath iliohypogastric nerve 32.When fabricated from a shape memory alloy, the body temperature ofpatient 10 may heat fixation structure 105 above the recovery shapetemperature. In another example, the fixation structure may beconstrained in a flat manner using a surgical tool or hand and, whenreleased, wraps around the nerve.

FIG. 10C is a cross sectional view of microelectrode 106 with fixationsstructure 105 wrapped substantially around iliohypogastric nerve 32. Forexample, as fixation structure 105 is warmed above its recovery shapetemperature, fixation structure 105 recovers its initial shape, i.e., asubstantially closed cylinder or ring. As shown in FIG. 10C, in someembodiments, fixation structure 105 may not close completely. However,fixation structure 105 may at least wrap partially aroundiliohypogastric nerve 32 in order to secure microstimulator 106 to thenerve site. Removing microelectrode 106 may be easier when fixationstructure 105 does not completely wrap around iliohypogastric nerve 32because the gap between the ends of fixation structure 105 may providean area to insert a tool that aids in removal. In alternativeembodiments, fixation structure 105 may wrap completely aroundiliohypogastric nerve 32.

In the illustrated example, a gap 109 exists between iliohypogastricnerve 32 and fixation structure 105. Gap 109 may be filled with tissueor fluids and may provide a buffer that prevents microstimulator 106from damaging iliohypogastric nerve 32. Alternatively, fixationstructure 105 may be sized to wrap around iliohypogastric nerve 32 suchthat there is substantially no gap between fixation structure 105 andiliohypogastric nerve 32.

FIG. 11 is cross-sectional view of a microstimulator 140 implantedwithin, for example, tissue 141 proximate or adjacent to iliohypogastricnerve 32. Housing 142 of microstimulator 140 is embedded in tissue 141proximate to iliohypogastric nerve 32 and includes circuit board 144,power source 146, and electrodes 148 and 149. Housing 142 is in theshape of a rounded capsule and includes a smooth surface. The onlystructure extending from housing 142 are electrodes 148 and 149.Electrodes 148 and 149 may protrude slightly from housing 142 or,alternatively, may be integrated into housing 142 to apply electricalstimulation to tissue 141. Electrodes 148 and 149 may be constructed aspads, as shown in FIG. 11, or as ring electrodes, as shown in FIG. 12.Microstimulator 140 rests in wall cavity 150 formed within externalfascia 141. As previously described, microstimulator 140 may have acylindrical shape with a diameter of less than or equal to approximately2 cm and a length of less than or equal to approximately 5 cm.

Circuit board 144, power source 146, and electrodes 148 and 149 may besimilar to respective circuit board 130, power source 132, andelectrodes 108 of FIGS. 11A-C. Differences between these components ofeach embodiment may relate to the size or shape of each component.Therefore, electrodes 148 and 149 apply electrical stimulation undercontrol of circuit board 144. Power source supplies operating power tocircuit board 144. Circuit board 144 may select stimulation parametersand cause electrodes 148 and 149 to apply electrical pulses with theselected parameters according to schedules stored in memory. Circuitboard 140 receives control signals from IMD 108, external programmer109, or both by wireless telemetry. In some embodiments, one ofelectrodes 148 and 149 may comprise a sensor or microstimulator 140 mayadditionally include a sensor that detects a physiological parameter. Insuch embodiments, the sensor may sense a change in a physiologicalparameter. Processing electronics on circuit board 144 detects thechange and causes electrodes to apply electrical stimulation in responseto the change.

Implanting microstimulator 140 within tissue 141 proximate toiliohypogastric nerve 32 may be a simple method for securing electrodes148 and 149. In some embodiments, a plurality of microstimulatorssimilar to microstimulator 140 may be implanted and apply electricalstimulation to iliohypogastric nerve 32 in a coordinated manner or in amanner independent of each other.

FIG. 12 is a schematic diagram illustrating implantation ofmicrostimulator 140 within tissue 141 of iliohypogastric nerve 32.Microstimulator 140 may be implanted through endoscopic, laparoscopic,or similar minimally invasive techniques. A surgeon may make a smallinguinal incision in patient 10 and guides microstimulator 140 withinneedle 152 to tissue 141. Needle 152 may be constructed of a metal alloyand comprise a hollow cylinder and a pointed distal end for puncturingthe skin of patient 10. Needle 152 includes microstimulator 140 and afluid or push rod to force microstimulator 140 out of the needle. Anexemplary fluid may be saline or other biocompatible fluid.

Once needle 152 in positioned at the appropriate location with respectto iliohypogastric nerve 32, the surgeon may force microstimulator 140into place. Removing needle 152 from tissue 141 proximate toiliohypogastric nerve 32 allows tissue 141 to close and surroundmicrostimulator 140. When implanting microstimulator 140, tissue 141should not be breached in order to prevent iliohypogastric nerve 32 frombeing damaged.

In other embodiments, microstimulator 140 may be implanted through moreinvasive procedures which expose iliohypogastric nerve 32. As previouslydescribed, multiple microstimulators may be implanted in tissue 141proximate to iliohypogastric nerve 32 to apply electrical stimulation toa larger area.

FIG. 13 is a functional block diagram illustrating various components ofan example microstimulator 106 (FIG. 6) or microstimulator 140 (FIG.11). In the example of FIG. 9, microstimulator 140 includes a processor160, memory 162, pulse generator circuitry 164, telemetry interface 168,power source 166 and electrodes 165. Pulse generator circuitry 164 maybe carried on a circuit board, along with processor 160, memory 162, andtelemetry interface 168. Memory 162 may store instructions for executionby processor 160, stimulation parameters, e.g., electrode polarity,pulse width, pulse rate, and amplitude, and schedules for deliveringelectrical stimulation. Memory 162 may include separate memories forstoring instructions, stimulation parameter sets, and schedules. Memory162 may comprise any form of computer-readable media such as magnetic oroptical tape or disks, solid state volatile or non-volatile memory,including random access memory (RAM), read only memory (ROM),electronically programmable memory (EPROM or EEPROM), or flash memory.

Processor 160 controls pulse generator circuitry 164 to deliverelectrical stimulation via electrodes 165. Electrodes 165 may compriseany number and type of electrodes previously described, i.e., electrodes108 (FIG. 6) and electrodes 148 and 149 (FIG. 11). An exemplary range ofstimulation pulse parameters likely to be effective in treating postvasectomy pain, iliohypogastric neuralgia, and other conditions thatcause long term pain in the testicles, groin, or abdomen when applied tothe iliohypogastric nerve are as follows: pulse widths betweenapproximately 10 and 5000 microseconds, more preferably betweenapproximately 100 and 1000 microseconds and still more preferablybetween 180 and 450 microseconds; voltage amplitudes betweenapproximately 0.1 and 50 volts, more preferably between approximately0.5 and 20 volts and still more preferably between approximately 1 and10 volts; and frequencies between approximately 0.5 and 500 hertz, morepreferably between approximately 10 and 250 hertz and still morepreferably between approximately 50 and 150 hertz. The pulses may bealternating current (ac) pulses or direct current (dc) pulses, and maybe mono-phasic, bi-phasic, or multi-phasic in various embodiments.

Processor 160 also controls telemetry interface 168 to receiveinformation from IMD 108, external programmer 109, or both. Telemetryinterface 168 may communicate via wireless telemetry, e.g., RFcommunication, on a continuous basis, at periodic intervals, or uponrequest from the implantable stimulator or programmer. Processor 160 mayinclude a single or multiple processors that are realized bymicroprocessors, Application-Specific Integrated Circuits (ASIC),Field-Programmable Gate Arrays (FPGA), or other equivalent integrated ordiscrete logic circuitry.

Power source 166 delivers operating power to the components of theimplantable microstimulator. As mentioned previously, power source 166may include a small rechargeable or non-rechargeable battery and a powergeneration circuit to produce the operating power.

FIG. 14 is a schematic diagram illustrating another configuration forexample system 100 of FIG. 7. In particular, rather than being implantedalong iliohypogastric nerve 33, electrodes 104 are illustrated in FIG.14 as being implanted perpendicular to iliohypogastric nerve 33.Implanting electrodes 104 perpendicular to iliohypogastric nerve 33 mayprovide certain advantages. For example, when implanted as shown,electrodes 104 may more effectively apply electrical stimulation to apoint along iliohypogastric nerve 33 instead of applying electricalstimulation along a length or portion of iliohypogastric nerve 33.Patient 10 may experience a more complete relief of pain or fewerunwanted side effects as a result of applying electrical stimulation inthis manner. The invention is not limited to the illustratedembodiments. Instead, electrodes 104 may be implanted at any orientationwith respect to iliohypogastric nerve 33.

FIG. 15 is a flow chart illustrating a technique for applying electricalstimulation to an iliohypogastric nerve of a patient using animplantable electrode. Any of the previously described electrodes, i.e.,cuff electrodes 16 and 17 (FIG. 1), electrodes 104 carried by lead 102(FIG. 6), microstimulator 106 (FIG. 6), and microstimulator 140 (FIG.7), may be implanted in accordance with the steps of the illustratedflow chart. The flow of events begins with the surgical procedure forimplanting the electrode. The surgical procedure for exposing theiliohypogastric nerve for lead placement is well defined and may beused. Specifically, the surgeon makes an inguinal incision (170) as usedfor standard iliohypogastric denervation or hernia repair.

The surgeon identifies the iliohypogastric nerve (172) and implants anelectrode adjacent to the iliohypogastric nerve (174). When implanting acuff electrode, the surgeon may elevate the iliohypogastric nerve andwrap the cuff electrode around the iliohypogastric nerve. If thefixation structure of the cuff electrode is formed from a shape memoryalloy, the body temperature of the patient may cause the fixationstructure to recover its initial shape, i.e., a substantially closedcylinder or ring shape sized to fit around the iliohypogastric nerve. Inany case, the cuff electrode may wrap at least partially around theiliohypogastric nerve thereby securing the cuff electrode to theiliohypogastric nerve.

When implanting lead 102 carrying electrodes 104, fixation elements suchas hooks, barbs, helical structures, tissue ingrowth mechanisms, orother anchoring mechanisms may secure lead 102 to the iliohypogastricnerve or tissue proximate to the iliohypogastric nerve. Leads carryingelectrodes may provide distinct advantages due to the number ofelectrodes available to apply electrical stimulation. For example, leadsare available that carry eight, sixteen, or more electrodes which can beused to apply electrical stimulation in various groups or independentlyof each other. Further, because the electrodes may be positioned along asubstantial length of the lead, the electrodes may apply electricalstimulation along a larger area of the iliohypogastric nerve.

The surgeon may implant microstimulator 106 similar to cuff electrodes16 and 17 because the fixation structure of microstimulator 106 mayoperate in the same manner as the fixation structure of cuff electrodes16 and 17. In contrast, the surgeon may implant microstimulator 140within tissue proximate or adjacent to the iliohypogastric nerve using aneedle. The needle may comprise a hollow cylinder and a pointed distalend for puncturing the skin of the patient and a fluid to forcemicrostimulator 140 out of the needle. Accordingly, the surgeon may notneed to make an inguinal incision when implanting microstimulator 140within the tissue proximate to the iliohypogastric nerve. Rather, oncethe needle is positioned at the appropriate location with respect to theiliohypogastric nerve, the surgeon forces microstimulator 140 into placeby depressing the plunger of the needle thereby forcing the fluid andmicrostimulator out of the needle.

Removing the needle from the tissue allows the tissue to close andsurround microstimulator 140. Consequently, microstimulator 140 may beimplanted with a minimally invasive surgical procedure. Additionally, insome embodiments, the surgeon may implant a plurality ofmicrostimulators along the iliohypogastric nerve. The microstimulatorsmay provide electrical stimulation independently or on a coordinatedbasis.

In general, the implantation techniques may be used to implantelectrodes proximate to an anterior or lateral cutaneous branch of oneor both iliohypogastric nerves or one or both iliohypogastric nerves,i.e., above the branch point of the iliohypogastric nerves. Implantingan electrode proximate to a region of the iliohypogastric nerve abovethe branch point may provide paresthesia to a larger area of the patientbecause electrical stimulation is applied further upstream of thecentral nervous system (CNS).

In any case, after implanting the electrode, the surgeon may create asubcutaneous pocket in the abdomen of the patient (1 76) and implant anIMD, such as IMD 28 (FIG. 1) or IMD 108 (FIG. 6), within thesubcutaneous pocket (178). In some embodiments, the IMD may beminiaturized and implanted within the scrotum of the patient. Thesurgeon may then tunnel the electrode lead through the tissue in thepatient to the implantation site and connect the lead to the implantedelectrode(s) (180). Notably, microstimulators 106 and 140 may wirelesslycommunicate with external programmer 109 to receive control signals and,thus, not require an IMD.

When the surgical implantation procedure is complete, the implantedelectrodes may apply electrical stimulation to deliver therapy (182) theiliohypogastric nerve. Applying electrical stimulation to theiliohypogastric nerve may block pain signals from the penis, testicles,and the associated scrotal area from reaching the CNS. The painexperienced by the patient may be uni-lateral or bi-lateral.Consequently, electrodes may be implanted adjacent to one or bothiliohypogastric nerves of a patient. The pain experienced by the patientmay also be constant or intermittent, or spontaneous or exacerbated byphysical activities and pressure. Thus, the implanted electrodes mayapply electrical stimulation on demand, such as in response to a controlsignal received from a patient or clinician programmer, or in accordancewith preprogrammed cycles or schedules.

Electrical stimulation of the iliohypogastric nerve may provide mayprovide substantial relief of pelvic pain experienced by male and femalepatients, including urogenital pain or other forms of pelvic pain. Inmale patients, for example, electrical stimulation of theiliohypogastric nerve may relieve a variety of pelvic pain conditionssuch as chronic groin pain, post vasectomy pain, iliohypogastricneuralgia, and other conditions that cause long term (chronic) pain inthe testicles, groin, or abdomen. For female patients, electricalstimulation of the iliohypogastric nerve may alleviate a variety ofpelvic pain conditions such as pain resulting from surgical procedures,vulvodynia, interstitial cystitis (painful bladder syndrome), adhesions,endometriosis, and pelvic congestion. Accordingly, although theinvention has been primarily described with respect to male patients,the invention is not so limited and may be readily applied to femalepatients for similar relief of pain symptoms.

When implemented in software, the functionality ascribed to the systemsand devices described in this disclosure may be embodied as instructionson a computer-readable medium such as random access memory (RAM),read-only memory (ROM), non-volatile random access memory (NVRAM),electrically erasable programmable read-only memory (EEPROM), FLASHmemory, magnetic media, optical media, or the like. The instructions areexecuted to support one or more aspects of the functionality describedin this disclosure

Many embodiments of the invention have been described. Variousmodifications may be made without departing from the scope of theclaims. These and other embodiments are within the scope of thefollowing claims.

1. A method comprising applying electrical stimulation to aniliohypogastric nerve of a patient via an implanted electricalstimulation device.
 2. The method of claim 1, further comprisingapplying the electrical stimulation to the iliohypogastric nerve at apoint prior to the iliohypogastric nerve branching to form an anteriorcutaneous nerve branch and a lateral cutaneous nerve branch.
 3. Themethod of claim 1, further comprising applying the electricalstimulation to at least one of an anterior cutaneous nerve branch and alateral cutaneous nerve branch of the iliohypogastric nerve.
 4. Themethod of claim 1, further comprising applying electrical stimulation tofirst and second iliohypogastric nerves of a patient via at least theimplanted electrical stimulation device.
 5. The method of claim 1,wherein the electrical stimulation device delivers electricalstimulation selected to alleviate pelvic pain.
 6. The method of claim 5,wherein the pelvic pain includes at least one of chronic groin pain,chronic testicular pain (CTP), post vasectomy pain, iliohypogastricneuralgia, vulvodynia, and interstitial cystitis.
 7. The method of claim1, wherein the electrical stimulation device comprises an electrodeconfigured to at least partially engage a portion of the iliohypogastricnerve.
 8. The method of claim 7, wherein the electrode includes at leastone of a cuff electrode, a ring electrode, a planar electrode or anelectrode on a leadless stimulator.
 9. The method of claim 7, whereinthe electrode includes a cuff electrode including a cuff-like fixationstructure and one or more electrodes.
 10. The method of claim 9, whereinthe cuff electrode is mounted to an implantable medical lead coupled tothe implantable electrical stimulation device.
 11. The method of claim9, wherein the implantable electrical stimulation device includes aleadless stimulator, and the cuff electrode is mounted to the leadlessstimulator.
 12. The method of claim 1, wherein the implantableelectrical stimulation device includes a leadless stimulator sized forat least partial implantation within tissue proximate to theiliohypogastric nerve of the patient.
 13. A system comprising: animplantable electrical stimulation device that generates electricalstimulation selected to alleviate pelvic pain; and an electrode coupledto the electrical stimulation device at a position adjacent to aniliohypogastric nerve of a patient.
 14. The system of claim 13, whereinthe electrical stimulation is selected to alleviate pelvic painincluding at least one of chronic groin pain, chronic testicular pain(CTP), post vasectomy pain, iliohypogastric neuralgia, vulvodynia, andinterstitial cystitis.
 15. The system of claim 13, further comprising afixation structure that positions the electrode adjacent to theiliohypogastric nerve.
 16. The system of claim 15, wherein the fixationstructure includes a cuff-like structure sized and shaped to at leastpartially enclose a portion of the iliohypogastric nerve, wherein thecuff-like structure carries the electrode for placement proximate theiliohypogastric nerve.
 17. The system of claim 13, wherein the electrodeis positioned to apply the electrical stimulation to the iliohypogastricnerve at a point prior to branching to form an anterior cutaneous nervebranch and a lateral cutaneous nerve branch.
 18. The system of claim 13,wherein the electrode is positioned to apply the electrical stimulationto at least one of an anterior cutaneous branch and a lateral cutaneousbranch of the iliohypogastric nerve.
 19. The system of claim 13, whereinthe electrode includes at least a first electrode and a secondelectrode, the first electrode being positioned to apply the electricalstimulation to a first iliohypogastric nerve of the patient and thesecond electrode being positioned to apply the electrical stimulation toa second iliohypogastric nerve of the patient.
 20. The system of claim13, wherein the electrode includes at least one of a cuff electrode, aring electrode, a planar electrode or an electrode on a leadlessstimulator.
 21. The system of claim 20, wherein the cuff electrode ismounted to an implantable medical lead coupled to the implantableelectrical stimulation device.
 22. The system of claim 20, wherein theimplantable electrical stimulation device includes a leadlessstimulator, and the cuff electrode is mounted to the leadlessstimulator.
 23. A method comprising applying electrical stimulation toat least a portion of an iliohypogastric nerve of a patient to alleviatepelvic pain.
 24. The method of claim 23, further comprising applyingelectrical stimulation to first and second iliohypogastric nerves of apatient via the implanted electrical stimulation device.
 25. The methodof claim 23, wherein the electrical stimulation device deliverselectrical stimulation selected to alleviate at least one of chronicgroin pain, chronic testicular pain (CTP), post vasectomy pain,iliohypogastric neuralgia, vulvodynia, and interstitial cystitis.